A structural approach to the non-blocking supervisory control of discrete-event systems

Many practical and important systemic properties of manufacturing systems, like deadlock freeness, liveness, and reversibility, can be formulated as the non-blocking property of discrete-event systems. It can be difficult, however, to verify non-blocking or design a supervisor to guarantee non-blocking control because of state size explosion in the concurrency model. In this paper, we present sufficient conditions for the computation of (small) model abstractions that preserve the non-blocking property. As a consequence, hierarchical and decentralized control structures can be flexibly integrated, and the proposed approach can synthesize maximally permissive and non-blocking control with reduced computational effort. The solution is a group of decentralized supervisors that transparently displays control logic and admits relatively simple implementation.